Photodetectors are a generic name for semiconductor devices that are operated based on the theory that incident light energy is absorbed and converted into electric energy, with the concomitant generation of electrons and holes. Representative among photodetectors are solar cells and solar sensors.
Silicon is representative of Group IV elemental semiconductors while indium antimonide (InSb) and cadmium telluride (CdTe) are representative among Groups III to V and Groups II to VI compound semiconductors, respectively. Because those semiconductors have respective energy band gaps, they find applications in different fields according to wavelength of interest.
Studies have been directed toward improving the quantum efficiency of photodetectors, with T. Ebbesen as a central figure. He reported that when light is incident on a metallic thin film in which regular arrays of nanoscale apertures are formed, light with a specific wavelength band is filtered due to surface plasmon, with enhanced light transmission through the metallic film. Since the report, many similar studies have followed.
Given such a metallic nanostructure, a photodetector, however, has a significantly reduced area on which light can be incident, and greatly differs in plasmon effect according to the incident angle of light.
There is therefore a need for a method by which a plasmon structure is applied to a photodetector without the above-mentioned problems.